1. Field of the Invention
The present invention relates to a speech recognition apparatus, a speech recognition method, and a speech recognition program for recognizing sequential words uttered by a user.
2. Description of Related Art
A speech recognition apparatus is deployed in a main storage (main memory (hereinafter, referred to as a “memory”), in which a central processing unit (CPU) can directly read or write word dictionary data containing a great amount of words, so as to be used for speech recognition processing. In a conventional speech recognition apparatus, a word dictionary is divided into a plurality of files and recorded in an auxiliary storage such as an HDD, a DVD, or an ROM, and only a required file is read from the auxiliary storage to a memory for recognition processing. This can suppress the capacity of a memory to be used for speech recognition processing. However, while the word dictionary data is being read (loaded) from the auxiliary storage into the memory, recognition processing cannot proceed. This causes a delay in the speech recognition processing.
For example, in an address recognition apparatus, a prefecture name dictionary and a city name dictionary are recorded in an auxiliary storage respectively as files. When recognizing a speech in which a prefecture name and a city name are uttered sequentially (or example, “AICHIKEN, NAGOYASHI”), the address recognition apparatus recognizes a prefecture name “AICHIKEN”, and then, reads a city name dictionary, corresponding to the prefecture name, to a memory. While reading the city name dictionary, the address recognition apparatus cannot proceed with recognition processing until the read is completed. Consequently, a delay is caused in address recognition processing.
A speech recognition apparatus that takes measures against such a delay has been proposed (see, for example, JP 2002-268673 A). The speech recognition apparatus performs matching processing using matching data read from a RAM in advance, while reading dictionary data from an auxiliary storage such as a DVD. The read dictionary data is recorded in delay matching data recording means, and the matching processing using data recorded in the delay matching data recording means is performed after the read is completed. After this, the delay matching data and the matching data are merged.
However, the above-mentioned speech recognition apparatus needs to merge results during matching with results obtained after the matching with a delay. Consequently, there has been a demand for a method for reducing a delay in processing caused by a waiting time for reading dictionary data from an auxiliary storage, by a method different from that of the above-mentioned speech recognition apparatus.